Twice in recent months, authorities have raided operations where finches were kept to attack each other for onlookers who bet on which birds would survive the matches.

PET TALK: Bird fighters harder to detect in 'underground culture'

"I understand it sounds odd," says Tim Rickey, the ASPCA's director of field investigations. "But cruelty is cruelty, and the suffering that's part of this practice is horrible."

Moreover, authorities worry about public safety. "The individuals who enjoy this kind of brutality, who attend these fights should be regarded as very dangerous," he says. "They're the same type of people who enjoy dog fighting and rooster fighting. There may be drugs or arms, and criminal backgrounds."

Increased public awareness and reporting have made dog and rooster fighting riskier, Rickey says. Finches are much cheaper to raise and keep, they're quieter, and they're easier to transport and secret away, he says.

Most of the birds seized in the busts in Shelton, Conn., and Ashland, Mass., were saffron finches, 6-inch songbirds indigenous to parts of South America, which sell for $120 and more a pair in the USA.

But in tight-quarters matches, two males are placed in a segmented cage with a female to bring them to a frenzied state. The separation barrier is removed, and fighting continues until one bird is dead or mortally wounded.

Many of the seized finches' beaks had been filed to razor sharpness.

In the Connecticut raid last summer, 19 men were arrested and 150 birds seized. In Massachusetts last month, more than 20 finches were seized, and Advertisement By Jodie Mozdzer, Valley Independent Sentinel

This injured finch was found after authorities raided a suspected finch-fighting ring.

investigations into the 20 people living in the house continue.

Many of the people apprehended in both busts were Brazilians. Brazil has long had a culture of finch fighting, but the practice was outlawed two decades ago.

Rickey suspects bird fighting extends beyond geography or cultures. "I have no reason to believe that these are the only two such operations in the country," he says.

"Trends like this, once they get kicked off, don't take much time to catch on."